A multifunctional use of bis(methylene)bis(5-bromo-2-hydroxyl salicyloylhydrazone): from metal sensing to ambient catalysis of A3 coupling reactions

Peewasan, Krisana; Merkel, Marcus; Fuhr, Olaf; Anson, Christopher E.; Powell, Annie K.

doi:10.1039/d0ra07687b

Cited by 7 publications

(3 citation statements)

References 32 publications

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“…Conversion to the desired product was complete within 16 h at room temperature under an Ar atmosphere and a significant improvement over our previous work (72 h). The present protocol is, to the best of our knowledge, , an example of a Cu(II) A 3 -coupling catalyst that is efficient at room temperature over a relatively short time. The scope of the reaction is shown in Figure , applicable to aliphatic aldehydes/secondary amines and alkynes.…”

Section: Resultsmentioning

confidence: 99%

Room-Temperature Cu(II) Radical-Triggered Alkyne C–H Activation

Devonport

Sully

Boudalis

et al. 2021

JACS Au

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A dimeric Cu(II) complex [Cu(II) 2 L 2 (μ 2 -Cl)Cl] (1) built from an asymmetric tridentate ligand (2-(((2aminocyclohexyl)imino)methyl)-4,6-di-tert-butylphenol) and weakly coordinating anions has been synthesized and structurally characterized. In dichloromethane solution, 1 exists in a monomeric [Cu(II)LCl] (1′) (85%)−dimeric (1) (15%) equilibrium, and cyclic voltammetry (CV) and electron paramagnetic resonance (EPR) studies indicate structural stability and redox retention. Addition of phenylacetylene to the CH 2 Cl 2 solution populates 1′ and leads to the formation of a transient radical species. Theoretical studies support this notion and show that the radical initiates an alkyne C−H bond activation process via a fourmembered ring (Cu(II)−O•••H−C alkyne ) intermediate. This unusual C−H activation method is applicable for the efficient synthesis of propargylamines, without additives, within 16 h, at low loadings and in noncoordinating solvents including late-stage functionalization of important bioactive molecules. Single-crystal X-ray diffraction studies, postcatalysis, confirmed the framework's stability and showed that the metal center preserves its oxidation state. The scope and limitations of this unconventional protocol are discussed.

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Section: Resultsmentioning

confidence: 99%

Room-Temperature Cu(II) Radical-Triggered Alkyne C–H Activation

Devonport

Sully

Boudalis

et al. 2021

JACS Au

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“…In 2020, Peewasan and Powell reported a dimeric Cu(II) complex formulated as [Cu 2 (H 5 L)(NO 3 ) 2 ]NO 3 •solv (9) [121], which was found to catalyse the A 3 coupling reaction. The protocol proceeds at room temperature for 24 h in i-PrOH and 1% catalyst loading with a good scope; however, no products were obtained when the aromatic and/or aliphatic primary amines were used.…”

Section: Scheme 57 (Left)mentioning

confidence: 99%

Metal-Catalysed A3 Coupling Methodologies: Classification and Visualisation

2022

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The multicomponent reaction of aldehydes, amines, and alkynes, known as A3 coupling, yields propargylamines, a valuable organic scaffold, and has received significant interest and attention in the last years. In order to fully realise the potential of the metal-based catalytic protocols that facilitate this transformation, we summarise substrates, in situ and well-characterised synthetic methods that provide this scaffold and attempt a monumental classification considering several variables (Metal, Coordinating atom(s), Ligand type and name, in-situ or well-characterised, co-catalyst, catalyst and ligand Loading (mol%), solvent, volume, atmosphere, temperature, microwave, time, yield, selectivity (e.e. d.r.), substrate name, functionality, loading (amines, aldehydes, alkynes), and use of molecular sieves). This pioneering work creates a valuable database that contains 2376 entries and allows us to produce graphs and better visualise their impact on the reaction.

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“…etc [51]. and multifunctional Cu, Ni, Co, Fe metal complexes designed from bis(methylene) bis(5-bromo-2hydroxy) salicyloylhydrazone ligand have displayed excellent catalytic activity in propargylamines synthesis [52]. Unfortunately, these catalytic systems have disadvantages such as tedious workup procedure, di culty in catalyst puri cation and recyclability [53].…”

Section: Introductionmentioning

confidence: 99%